ik this is a shitpost but that's like the worst possible way to handle that situation
i'm like a third-generation none, my parents were both raised secular and their marriage was officiated by a guy from the a.h.a., but i had some christian classmates in like kindergarten or first grade (public school in california) and i sorta half remember asking my mom some question about something i'd heard them say at some point or another, and what she did was she explained to me (in 5yo detail, anyway) what christianity even was, which i didn't really understand at that point, and that was enough to make it clear to me how silly it all was.
one of the easiest ways to figure out who to trust, imo, is looking for who can most accurately and fairly describe what their opponents' argument is. trying to hide it away from a kid who's looking for answers is just going to make it more intriguing. going over it in detail makes it clear what the problems are.
e: damn, who'd i piss off